Utils: Declare mathChars and nextItemIdx where they're used

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I33cce402bb610114df0444fe1bed28662ac80594
diff --git a/src/Utils.cpp b/src/Utils.cpp
index c19ec12..dd13113 100644
--- a/src/Utils.cpp
+++ b/src/Utils.cpp
@@ -247,10 +247,7 @@
             continue;
         }
 
-        constexpr const std::array<char, 5> mathChars = {'+', '-', '%', '*',
-                                                         '/'};
         size_t start = find.begin() - strPtr->begin();
-        size_t nextItemIdx = start + templateName.size() + 1;
 
         // check for additional operations
         if (!start && find.end() == strPtr->end())
@@ -258,6 +255,11 @@
             std::visit([&](auto&& val) { keyPair.value() = val; }, propValue);
             return ret;
         }
+
+        constexpr const std::array<char, 5> mathChars = {'+', '-', '%', '*',
+                                                         '/'};
+        size_t nextItemIdx = start + templateName.size() + 1;
+
         if (nextItemIdx > strPtr->size() ||
             std::find(mathChars.begin(), mathChars.end(),
                       strPtr->at(nextItemIdx)) == mathChars.end())